The document discusses several POSIX feature test macros like _POSIX_JOB_CONTROL and _POSIX_SAVED_IDS. It explains that these macros define whether a system supports features like job control and each process saving UID and GID. It also discusses using sysconf(), pathconf() and fpathconf() to check runtime limits and configuration values set by these macros.
I am Anne L. I am an Operating System Assignment Expert at programminghomeworkhelp.com. I hold a Ph.D. in Programming, Auburn University, USA. I have been helping students with their homework for the past 8 years. I solve assignments related to Operating systems.
Visit programminghomeworkhelp.com or email support@programminghomeworkhelp.com.
You can also call on +1 678 648 4277 for any assistance with Operating System Assignments.
I am Joseph G . I am a Programming Assignment Expert at programminghomeworkhelp.com. I hold a Ph.D. Programming, Schiller International University, USA. I have been helping students with their homework for the past 8 years. I solve assignments related to Programming.
Visit programminghomeworkhelp.com or email support@programminghomeworkhelp.com.
You can also call on +1 678 648 4277 for any assistance with Programming Assignments.
I am Burrows N. I am an Operating System Assignment Expert at programminghomeworkhelp.com. I hold a PhD. in Programming from, University Of Chicago, USA. I have been helping students with their homework for the past 4 years. I solve assignments related to Operating systems.
Visit programminghomeworkhelp.com or email support@programminghomeworkhelp.com.
You can also call on +1 678 648 4277 for any assistance with Operating System Assignments.
4Developers 2018: The turbulent road to byte-addressable storage support at t...PROIDEA
The advent of new persistent memory technologies that are extremely fast and accessible at the CPU level is an opportunity to rethink many of the assumptions that were made during the design of storage interfaces in programming languages and supporting libraries. Many of the currently employed solutions will need to be designed from scratch with the new paradigms in mind to achieve full benefit of using this type of memory. But radical changes are never easy, and this one is no exception. Many researchers and industry experts have been working on this topic for a long time, and here's what they came up with. This lecture will introduce the broader aspects of persistent memory and what is currently being done to enable existing operating systems and programming languages to support this new type of technology. It will focus on C++ related activities and discuss the standardization efforts currently planned for full native language support.
I am Joe L. I am a Computer Science Assignment Help Expert at programminghomeworkhelp.com. I hold a Ph.D. in Programming from, University of Chicago, USA. I have been helping students with their homework for the past 9 years. I solve assignments related to Computer Science.
Visit programminghomeworkhelp.com or email support@programminghomeworkhelp.com.
You can also call on +1 678 648 4277 for any assistance with Computer Science assignments.
I am Irene. I am a Computer Science Assignment Help Expert at programminghomeworkhelp.com. I hold a Ph.D. in Computer Science from, California Institute of Technology. I have been helping students with their homework for the past 8 years. I solve assignments related to Computer Science.
Visit programminghomeworkhelp.com or email support@programminghomeworkhelp.com.
You can also call on +1 678 648 4277 for any assistance with Computer Science assignments.
various tricks for remote linux exploits by Seok-Ha Lee (wh1ant)CODE BLUE
Modern operating systems include hardened security mechanisms to block exploit attempts. ASLR and NX (DEP) are two examples of the mechanisms that are widely implemented for the sake of security. However, there exists ways to bypass such protections by leveraging advanced exploitation techniques. It becomes harder to achieve code execution when the exploitation originates from a remote location, such as when the attack originates from a client, targeting server daemons. In such cases it is harder to find out the context information of target systems and, therefore, harder to achieve code execution. Knowledge on the memory layout of the targeted process is a crucial piece of the puzzle in developing an exploit, but it is harder to figure out when the exploit attempt is performed remotely. Recently, there have been techniques to leverage information disclosure (memory leak) vulnerabilities to figure out where specific library modules are loaded in the memory layout space, and such classes of vulnerabilities have been proven to be useful to bypass ASLR. However, there is also a different way of figuring out the memory layout of a process running in a remote environment. This method involves probing for valid addresses in target remote process. In a Linux environment, forked child processes will inherit already randomized memory layout from the parent process. Thus every client connection made to server daemons will share the same memory layout. The memory layout randomization is only done during the startup of the parent service process, and not randomized again when it is forking a child process to handle client connections. Due to the inheritance of child processes, it is possible to figure out a small piece of different information from every connection, and these pieces can be assembled later to get the idea of a big picture of the target process's remote memory layout. Probing to see if a given address is a valid memory address in context of the target remote process and assembling such information together, an attacker can figure out where the libc library is loaded on the memory, thus allowing exploits to succeed further in code execution. One might call it brute force, but with a smart brute forcing strategy, the number of minimal required attempts are significantly reduced to less than 10 in usual cases. In this talk, we will be talking about how it is possible to probe for memory layout space utilizing a piece of code to put the target in a blocked state, and to achieve stable code execution in remote exploit attempt scenarios using such information, as well as other tricks that are often used in remote exploit development in the Linux environment.
http://codeblue.jp/en-speaker.html#SeokHaLee
Avec la version 9 sortie en septembre 2017, Java appuie sur la pédale ! Le rythme des livraisons passe à une version majeure tous les 6 mois. Java 10 est sorti en mars, prochaine version en septembre. Java 10 apporte le 'var' et l'inférence de type pour les variables locales. D'autres nouveautés sont en préparation : les constantes dynamiques, les classes de données, un nouveau switch à base de lambda, des interfaces fermées, de nouvelles choses du coté des génériques et bien plus encore.
Cela viendra-t-il en 11, 12, 15 ? Ne spéculons pas, mais quand ces nouveautés seront prêtes, elles sortiront en quelques mois. On se propose de présenter ces nouveautés, celles qui sont presque prêtes, celles qui seront prêtes bientôt, et celles qui ne seront pas prêtes avant un moment. Quels seront les impacts sur le langage, sur la JVM et donc sur les performances ? Que cela va-t-il nous apporter au quotidien, en tant que développeurs ? Quels seront les nouveaux patterns ? Voici le programme de cette présentation, avec des slides, du code, de la joie et de la bonne humeur !
I am Anne L. I am an Operating System Assignment Expert at programminghomeworkhelp.com. I hold a Ph.D. in Programming, Auburn University, USA. I have been helping students with their homework for the past 8 years. I solve assignments related to Operating systems.
Visit programminghomeworkhelp.com or email support@programminghomeworkhelp.com.
You can also call on +1 678 648 4277 for any assistance with Operating System Assignments.
I am Joseph G . I am a Programming Assignment Expert at programminghomeworkhelp.com. I hold a Ph.D. Programming, Schiller International University, USA. I have been helping students with their homework for the past 8 years. I solve assignments related to Programming.
Visit programminghomeworkhelp.com or email support@programminghomeworkhelp.com.
You can also call on +1 678 648 4277 for any assistance with Programming Assignments.
I am Burrows N. I am an Operating System Assignment Expert at programminghomeworkhelp.com. I hold a PhD. in Programming from, University Of Chicago, USA. I have been helping students with their homework for the past 4 years. I solve assignments related to Operating systems.
Visit programminghomeworkhelp.com or email support@programminghomeworkhelp.com.
You can also call on +1 678 648 4277 for any assistance with Operating System Assignments.
4Developers 2018: The turbulent road to byte-addressable storage support at t...PROIDEA
The advent of new persistent memory technologies that are extremely fast and accessible at the CPU level is an opportunity to rethink many of the assumptions that were made during the design of storage interfaces in programming languages and supporting libraries. Many of the currently employed solutions will need to be designed from scratch with the new paradigms in mind to achieve full benefit of using this type of memory. But radical changes are never easy, and this one is no exception. Many researchers and industry experts have been working on this topic for a long time, and here's what they came up with. This lecture will introduce the broader aspects of persistent memory and what is currently being done to enable existing operating systems and programming languages to support this new type of technology. It will focus on C++ related activities and discuss the standardization efforts currently planned for full native language support.
I am Joe L. I am a Computer Science Assignment Help Expert at programminghomeworkhelp.com. I hold a Ph.D. in Programming from, University of Chicago, USA. I have been helping students with their homework for the past 9 years. I solve assignments related to Computer Science.
Visit programminghomeworkhelp.com or email support@programminghomeworkhelp.com.
You can also call on +1 678 648 4277 for any assistance with Computer Science assignments.
I am Irene. I am a Computer Science Assignment Help Expert at programminghomeworkhelp.com. I hold a Ph.D. in Computer Science from, California Institute of Technology. I have been helping students with their homework for the past 8 years. I solve assignments related to Computer Science.
Visit programminghomeworkhelp.com or email support@programminghomeworkhelp.com.
You can also call on +1 678 648 4277 for any assistance with Computer Science assignments.
various tricks for remote linux exploits by Seok-Ha Lee (wh1ant)CODE BLUE
Modern operating systems include hardened security mechanisms to block exploit attempts. ASLR and NX (DEP) are two examples of the mechanisms that are widely implemented for the sake of security. However, there exists ways to bypass such protections by leveraging advanced exploitation techniques. It becomes harder to achieve code execution when the exploitation originates from a remote location, such as when the attack originates from a client, targeting server daemons. In such cases it is harder to find out the context information of target systems and, therefore, harder to achieve code execution. Knowledge on the memory layout of the targeted process is a crucial piece of the puzzle in developing an exploit, but it is harder to figure out when the exploit attempt is performed remotely. Recently, there have been techniques to leverage information disclosure (memory leak) vulnerabilities to figure out where specific library modules are loaded in the memory layout space, and such classes of vulnerabilities have been proven to be useful to bypass ASLR. However, there is also a different way of figuring out the memory layout of a process running in a remote environment. This method involves probing for valid addresses in target remote process. In a Linux environment, forked child processes will inherit already randomized memory layout from the parent process. Thus every client connection made to server daemons will share the same memory layout. The memory layout randomization is only done during the startup of the parent service process, and not randomized again when it is forking a child process to handle client connections. Due to the inheritance of child processes, it is possible to figure out a small piece of different information from every connection, and these pieces can be assembled later to get the idea of a big picture of the target process's remote memory layout. Probing to see if a given address is a valid memory address in context of the target remote process and assembling such information together, an attacker can figure out where the libc library is loaded on the memory, thus allowing exploits to succeed further in code execution. One might call it brute force, but with a smart brute forcing strategy, the number of minimal required attempts are significantly reduced to less than 10 in usual cases. In this talk, we will be talking about how it is possible to probe for memory layout space utilizing a piece of code to put the target in a blocked state, and to achieve stable code execution in remote exploit attempt scenarios using such information, as well as other tricks that are often used in remote exploit development in the Linux environment.
http://codeblue.jp/en-speaker.html#SeokHaLee
Avec la version 9 sortie en septembre 2017, Java appuie sur la pédale ! Le rythme des livraisons passe à une version majeure tous les 6 mois. Java 10 est sorti en mars, prochaine version en septembre. Java 10 apporte le 'var' et l'inférence de type pour les variables locales. D'autres nouveautés sont en préparation : les constantes dynamiques, les classes de données, un nouveau switch à base de lambda, des interfaces fermées, de nouvelles choses du coté des génériques et bien plus encore.
Cela viendra-t-il en 11, 12, 15 ? Ne spéculons pas, mais quand ces nouveautés seront prêtes, elles sortiront en quelques mois. On se propose de présenter ces nouveautés, celles qui sont presque prêtes, celles qui seront prêtes bientôt, et celles qui ne seront pas prêtes avant un moment. Quels seront les impacts sur le langage, sur la JVM et donc sur les performances ? Que cela va-t-il nous apporter au quotidien, en tant que développeurs ? Quels seront les nouveaux patterns ? Voici le programme de cette présentation, avec des slides, du code, de la joie et de la bonne humeur !
One of the tutorials I gave at University of Wollongong on inodes.
Describes direct, single, double and triple linking, and how that all ties together with addressable space.
The Raspberry Pi is a series of credit card–sized single-board computers developed in the UK by the Raspberry Pi Foundation with the intention of promoting the teaching of basic computer science in schools.
The original Raspberry Pi and Raspberry Pi 2 are manufactured in several board configurations through licensed manufacturing agreements with Newark element14 (Premier Farnell), RS Components and Egoman. These companies sell the Raspberry Pi online. Egoman produces a version for distribution solely in China and Taiwan, which can be distinguished from other Pis by their red colouring and lack of FCC/CE marks. The hardware is the same across all manufacturers.
The original Raspberry Pi is based on the Broadcom BCM2835 system on a chip (SoC), which includes an ARM1176JZF-S 700 MHz processor, VideoCore IV GPU, and was originally shipped with 256 megabytes of RAM, later upgraded (models B and B+) to 512 MB. The system has Secure Digital (SD) (models A and B) or MicroSD (models A+ and B+) sockets for boot media and persistent storage.
Language Enhancement in ColdFusion 8 - CFUnited 2007
Unit 1
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3. Darshan,S.J.B.I.T The POSIX Feature Test Macros 3. _POSIX_CHOWN_RESTRICTED: If the defined value is -1 ,users may change Ownership of files owned by them . If the value is not -1 ,then only the users with special privileges may change the Ownership of nay files on a system. If this constant is undefined in <unistd.h> header,user must use the pathconf() Or fpathconf() function. 4._POSIX_NO_TRUNC : If the defined values is -1 ,any long pathname passed to an API is truncated to _POSIX_NAME_MAX bytes,otherwise any error is generated. If this constant is undefined in <unistd.h> header,user must use the pathconf() Or fpathconf() function. 5._POSIX_VDISABLE: If the defined value is -1 ,then there is no disabling character for special charactersfor all terminal devices files. If this constant is undefined in <unistd.h> header,user must use the pathconf() Or fpathconf() function.
4. Darshan,S.J.B.I.T Show test macros #define _POSIX_SOURCE #define _POSIX_C_SOURCE 199309L #include <iostream.h> #include <unistd.h> int main() { #ifdef _POSIX_JOB_CONTROL cout<<“System supports job control”; #else cout<<“System does not support job control”; #endif . . . . }
5. Darshan,S.J.B.I.T Limits checking at compile time and at run time POSIX.1 & POSIX.1b define a set of system configuration limits in the form of Constant in <limits.h> header. Compile time limit Value Meaning _POSIX_NGROUP_MAX 0 Maximum number of supplement groups to which a process may belong . _POSIX_TZNAME_MAX 3 Maximum number of characters in a time zone name _ POSIX_CHILD_MAX 6 Maximum number of child processes that may created at any one time by a process _POSIX_LINK_MAX 8 Maximum number of links a file may have _ POSIX_STREAM_MAX 8 Maximum number of I/O streams that may be simultaneously by a process _ POSIX_NAME_MAX 14 Maximum number of characters allowed in a filename _POSIX_OPEN_MAX 16 Maximum number of file that may be opened simultaneously by a process _ POSIX_PATH_MAX 255 Maximum number of characters allowed in a pathname _POSIX_MAX_INPUT 255 Maximum size in bytes of terminal’s input queue _POSIX_MAX_CANON 255 Maximum size in bytes of terminal’s canonical input queue _POSIX_ARG_MAX 4096 Maximum length of argument to the exec functions including environment data. _ POSIX_SSIZE_MAX 32767 Maximum value that can be stored in an object of type ssize_t .
6. Darshan,S.J.B.I.T POSIX.1B CONSTANTS COMPILE TIME LIMIT VALUE MEANING _POSIX_AIO_MAX 1 The number of simultaneously asynchronous I/O operations. _POSIX_AIO_LISTIO_MAX 2 The number of I/O operations that can be specified in a list I/O call . _POSIX_MQ_OPEN_MAX 2 The number of message queues that can be open for a single process. _POSIX_MQ_PRIO_MAX 2 The maximum number of message priorities that can be assigned to messages _POSIX_RTSIG_MAX 8 The maximum number of realtime signal . _POSIX_TIMER_MAX 32 Maximum number of timers that can be used simultaneously number of timers. _POSIX_SIGQUEUE_MAX 32 Maximum number of realtime signals that a process may queue at any one time _POSIX_DELAYTIMER_MAX 32 Maximum number of overruns allowed per timer. _POSIX_SEM_NSEMS_MAX 256 Maximum number of semaphore s that may be used simultaneously per process _POSIX_SEM_VALUE_MAX 32767 The maximum value a semaphore may have
7. Darshan,S.J.B.I.T sysconf, pathconf & fpathconf To find out the actual implemented configuration limit system wide we can use sysconf,pathconf & fpathconf The prototype of these functions are: #include<unistd.h> long sysconf ( const int limit_name); long pathconf ( const char* pathname, int flimit_name); long fpathconf ( const int fdesc,int flimit_name); The sysconf is used to query general system configuration limits that are implemented on a given system. The pathconf & fpathconf are used to query file-related configuration limits.
8. Darshan,S.J.B.I.T The possible limited value by the sysconf function Limit value sysconf return data _ SG_ARG_MAX Maximum length of argument to the exec functions including environment data. _SC_AIO_LISTIO_MAX The number of I/O operations that can be specified in a list I/O call . _SC_AIO_MAX The number of simultaneously asynchronous I/O operations _SC_CHILD_MAX Maximum number of child processes that may created at any one time by a process _SC_CLK_TCK The number of clock ticks per second. _ SC_DELAYTIMER_MAX Maximum number of overruns allowed per timer _SC_JOB_CONTROL The POSIX_JOB_CONTROL value _SC_MQ_OPEN_MAX Maximum number of message queues per process _SC_MQ_PRIO_MAX Maximum priority value assignable to a message _SC_NGRUOP_MAX Maximum number of supplemental groups per process
9. Darshan,S.J.B.I.T The possible limited value by the sysconf function LIMIT VALUE sysconf return Data _SC_OPEN_MAX Maximum number of opened files per process _SC_RTSIG_MAX Maximum number of real time signals _SC_SAVED_IDS The _POSIX_SAVED_IDS value _ SC_SEM_NSEMS_MAX Maximum number of semaphores per process _SC_SIGQUEUE_MAX Maximum number of realtime signals that a process may queue at any one-time _SC_TIMERS The _POSIX_TIMERS Value _SC_VERSION The _POSIX_VERSION value.
10. Darshan,S.J.B.I.T The possible limited value by the pathconf & fpathconf function Limit value pathconf/fathconf return Data _ PC_CHOWN_RESTRICTED The _POSIX_CHOWN_RESTRICTED value. _PC_LINK_MAX Maximum number of links a file may have _PC_MAX_CANON Maximum size in bytes of terminal canonical input queue _PC_MAX_INPUT Maximum size in bytes of terminal input queue _PC_NO_TRUNC The _POSIX_NO_TRUNC value _PC_NAME_MAX Maximum length in bytes of a file name. _PC_PATH_MAX Maximum length in bytes of a pathname _PC_PIPE_BUF Maximum size of a block of data that may be automatically read from or written to a pipe file _PC_VDISABLE The _POSIX_VDISABLE value
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12. Darshan,S.J.B.I.T The X/Open Standards X/Open organization was formed by a group of European companies to propose a common OS interface for their computing systems. XPG3 – 1989 XPG4 – 1994 COSE (Common Open software Environment) formed in 1993 by HP, IBM, Novell, OSF and Sun Microsystems SPEC 1179 Incorporated in XPG4 as part of X/Open Common Application Environment
13. Darshan,S.J.B.I.T Unix & POSIX API”S UNIX systems provides a set of application programming interface(API”S) functions commonly known as system calls which may be called user’s programs to perform System specific functions. These fuctions allows user’s applications to directly to manipulate system objects such as files and processes that cannot be done by using standard C library functions. Functions of API”S 1.Determine system configuration and user Infromation 2.File Manipulation 3.Process creation & control. 4.Interprocess communication 5.Network Communication
14. Darshan,S.J.B.I.T What happens when an API’s is called When an API’s is invoked by a process,then execution context is switched by the kernel from a usermode to a kernel mode User mode : is the normal execution context of any user process. It allows the process to access its process-specific data only. Kernel mode : Is a protective execution environment that allows a user to access kernels data in a restricted manner. In general ,calling an API is more time consuming than calling a user function due to Context switching
15. Darshan,S.J.B.I.T API COMMON CHARACTERISTICS POSIX & UNIX API’s after performing the system functions returns an integer value which indicates the termination status of the execution. If an API returns -1 value,it means the API’s execution has failed,& global variable Declared in the <errno.h> header is set with an error code. A user process may call the perror function to print a message of the failure To the standard output. or It may call the strerror function returns a message string & the user process may Print that message in its preferred way.
16. Darshan,S.J.B.I.T ERROR STATUS CODE ERROR STATUS CODE Meaning EACCESS A process doesn't have access permission to perform an operation via an API EAGAIN An API was aborted because some system resource it requested was temporarily unavailable. So the API should be called again later EBADF An API was called with an Invalid file descriptor ECHILD A process doesnot have any child process which it can wait on EFAULT An API was passed an invalid address in one of its argument EINTR An API execution was aborted due to signal Interruption EIO I/O error occurred in a API execution ENOENT An invalid filename was specified to an API ENOEXEC An AP Couldn't execute a program via of the exec API EPERM An API was aborted because the calling process doesn't have the superuser privilege EPIPE An API attempted to write data to a pipe which has no reader ENOMEM An API was aborted because it could allocate Dynamic memory